The present invention relates to vehicle monitoring systems in general and, more particularly to an automatic vehicle monitoring system which utilizes a plurality of spaced magnetic fields positioned along a vehicle path to provide information concerning the vehicle.
Vehicle location, guidance and control systems which employ spaced magnets along the vehicle path are known in the art. Representative examples are described in U.S. Pat. Nos. 2,493,755, 3,085,646; 3,493,923; 3,609,678; and, 3,668,624. See also "DAIR - A New Concept In Highway Communications For Added Safety and Driving Convenience" by E. A. Hanysz et al, IEEE Transactions On Vehicle Technology, Vol. VT-16, No. 1, October 1967.
The practical implementation of the prior art magnetic coding vehicle monitoring systems presents a number of problems in terms of sensor sensitivity, noise discrimination and magnetic array configurations.
It is a general object of the invention to provide a practical automatic vehicle monitoring system which utilizes a plurality of spaced magnetic fields disposed along a vehicle path.
It is a specific object of the invention to provide a magnetic array configuration and coding which provides noise discrimination and optimum utilization of a given number of magnets.
It is another object of the invention to provide a magnetic field pickup coil construction which has sufficient sensitivity with a concomitant physical configuration that permits under vehicle mounting.
It is still another object of the invention to provide noise discrimination circuits which substantially eliminate the deleterious effects of magnetic noise.